A unique identifier : UUID GUID « Development Class « Java

1. Java
2. Development Class
3. UUID GUID

A unique identifier

     
/* 
 * This file is part of the Echo Web Application Framework (hereinafter "Echo").
 * Copyright (C) 2002-2009 NextApp, Inc.
 *
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 */


/**
 * A unique identifier.
 */
public class Uid {

    private static final String machineIdString = Integer.toHexString(new Object().hashCode());
    private static int globalCount = 0;
    
    private final int count = ++globalCount;
    private final long time = System.currentTimeMillis();
    
    /**
     * Generates a new identifier String.
     */
    public static final String generateUidString() {
        String idString = new Uid().toString();
        return idString;
    }

    /**
     * Generates a new identifier.
     */
    private Uid() {
        super();
    }
    
    /**
     * @see java.lang.Object#toString()
     */
    public String toString() {
        String timeString = Long.toHexString(time);
        String countString = Integer.toHexString(count);
        
        return machineIdString + "_" + timeString + "_" + countString;
    }
}

   
    
    
    
    
  

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